In the field of molecular biology, microarray chips, as represented by a biochip on which biopolymers such as DNAs or proteins are high-densely immobilized, have lately and rapidly become of interest. For an experiment using the microarray chip, numbers of supports (chips) with diverse types of elements (probes) immobilized thereon are produced. The elements on each chip are subjected to reaction with a sample (target) of a test subject. The difference of the reaction between the elements and the sample on one chip may be detected by a single experiment. The difference of the reaction between the same element collections on a plurality of chips may be detected by repeating experiments under different conditions.
In an experiment using a microarray chip, it is necessary to manage the information of diverse types of elements immobilized on the chip. The following methods are practically used for preparing a microarray chip: a method in which elements prepared in wells are immobilized on a support such as a glass slide by using a spotter (arrayer); and a method in which elements are synthesized on a support according to a semiconductor producing technique. In both methods, element information (i.e., which element is to be immobilized on which location on the chip) is prepared as data for preparing the microarray chip.
In an experiment using a microarray chip, the results of the experiment are obtained by detecting color development of part of the element collection immobilized on the chip. In detecting the color development, “the color intensities of the elements” are recorded based on the element information obtained for preparing the microarray chip. Then, the difference of color development between the elements and the difference of color development between the element collections on the chips are analyzed.
Since the shapes of the microarray chips are all identical, each individual microarray chip cannot be identified by its appearance, nor can the types of the DNAs immobilized on the chip be identified. As shown in FIG. 7, a method is suggested in which letters, numbers or symbols are printed or barcodes are provided as an index outside a element region 101 on a microarray chip 100 so as to specify the element information to be used for the microarray chip 100.
In specifying the element information to be used for each microarray chip by the method of printing letters, numbers, symbols or barcodes outside the element region of the chip, a mechanism for printing (or sticking) letters, numbers, symbols or barcodes on a chip is required. In addition, in using the microarray chip, mechanisms (or an interface that allows input by an operator) are also required for reading the letter, barcode or the like printed on the chip and for informing the same to an information processing system. As a result, cost of devices such as a letter or barcode reader, input error in case of manual input and the like have been the problems.
Regarding the above-described problems of conventional technique, the present invention aims at providing a microarray chip for which element information to be used can be specified without using letters, barcodes of the like. The present invention also aims at providing a method for indexing a microarray chip for specifying element information to be used for the microarray chip without requiring a special-purpose device for reading the element information such as a letter or barcode reader. The present invention further aims at providing a method for indexing a microarray chip, which enables automatic management of information of the elements on the microarray chip and use of experiment information.
According to the present invention, the above-described aims are accomplished by using some of the spots (element spots) arranged on the microchip array as an index (a microarray index) for managing the element information. According to the present invention, elements themselves are used as an index so that the index can be obtained together with the element information upon reading the microarray chip. Thus, there is no need of preparing a special device for reading the index.
Accordingly, a microarray chip of the invention is characterized by comprising a plurality of spots arranged in a predetermined positional relationship, wherein some of the plurality of spots provide index information for specifying the microarray chip.
The microarray chip of the invention is also characterized by comprising a plurality of element spots arranged in a predetermined positional relationship, wherein spots which provide index information for specifying the microarray chip are positioned along with the element spots.
The spots constructing the microarray index are preferably added with visible colorant beforehand to confirm the index before the experiment, to align the element region and the index region, and to confirm the chip reading direction.
When the microarray chip is prepared by immobilizing elements prepared in wells on a support such as a glass slide by using a spotter (arrayer), elements already bound with a luminescent substance or elements as index spots which allow accumulation of a luminescent substance on the element spots upon the microarray chip experiment are immobilized with the spotter. When the microarray chip is prepared by synthesizing elements on a support according to a semiconductor producing technique, elements which allow accumulation of a luminescent substance on the element spots upon the microarray chip experiment are synthesized on the support.
As described above, the spots used for constructing the index information include spots containing and spots not containing detective colorant, which the index information is based on the presence and absence of the detective colorant. The detective colorant which is used as a fluorescent label for hybridization reaction may be contained in the index spots prior to hybridization reaction, or may be contained in the target and be provided to the spots as a result of the hybridization reaction. The elements to be immbolized as a microarray index may be labeled with a detective colorant beforehand so as to allow the use of the microarray chip index before the experiment of reacting with the target.
In reading the microarray chip image with a microarray chip reader, the index information on the microarray chip are read simultaneously with the element information. By providing a microarray index at a predetermined position, the microarray index may be obtained from the readout image of the microarray chip after the reaction.
A method for indexing the microarray chip according to the present invention is a method for indexing a microarray chip comprising a plurality of spots arranged in a predetermined positional relationship, wherein some of the plurality of spots are used for maintaining index information.
A method for indexing the microarray chip according to the present invention is further a method for indexing a microarray chip comprising a plurality of spots arranged in a predetermined positional relationship, wherein some of the plurality of spots are used as index spots for maintaining index information, and the index information is reproduced by detecting the presence or absence of a detective colorant on the index spots.
In an experiment using a microarray chip where elements which allow accumulation of a luminescent substance on the element spots are immobilized or synthesized on a support, colored (‘on’) spots for constructing the microarray index are obtained by immobilizing or synthesizing, on a support, a substance that reacts with a substance labeled with a colorant which is present in a sample during the course of the experiment, or a substance that reacts with a substance labeled with a colorant added to the sample. Thus, spot detection is ensured.
Moreover, spot detection error can be avoided by providing parity spots. For example, information detected at the index spots is realigned into a two-dimensional matrix upon reproducing the index information, and part of the spot information of the realigned two-dimensional matrix is used as parity information. If necessary, microarray index may be duplicated by providing them at two positions in the element region, thereby avoiding spot detection error.
Database which uses the microarray as an index may be constructed for storing microarray chip information (preparation date, on-chip-spot location information, conditions of the experiment, etc.) and on-chip-element information (element index, experiment measurement information, etc.). The database also stores element information (index for referring to a public database, gene name, definition of the functions, DNA sequence, etc.) and links with information of the element on chip via the element index. By linking the actual microarray chip and the information in the database via the microarray index obtained from the microarray chip readout image, measurement information can automatically be input into the database.
Specifically, a database is constructed for storing a element information record, a microarray chip master record and an on-chip-element information record. Information of a element is recorded on the element information record where a element index is used as a master index. Information of the microarray chip is recorded on the microarray chip master record where the microarray index is used as a master record. The microarray index, a location of a spot on the microarray chip, element index of the element spotted on that location, and the information of measurement of the spot are recorded on the on-chip-element information record. The microarray chip is linked with the microarray chip master record via the microarray index maintained by the index spots, as well as to the on-chip-element information record. The on-chip-element information record is linked with the element information record via the element index.